74 PEOCEEDINGS OP THE GEOLOGICAL SOCIETY. [Dec. 21, 



1. On Lower Tertiaey Deposits recently exposed at Poktsmouth 

 By C. J. A. Meter, Esq., F.G.S. 



The excavations in progress at Portsmouth in furtherance of tlie 

 works known as the " Dockyard Extension Works," have exposed 

 to view, during the last three or four years, many fine and highly 

 interesting sections in the Lower Tertiaries. 



I propose to lay before the Society, by way of record, a brief 

 account of these sections, and of the numerous fossils which have 

 been obtained from them. 



The site of the " Extension Works " lies to the east and north- 

 east of the existing Dockyard. A description of the works them- 

 selves would be out of place in this paper ; I shall therefore confine 

 my mention of them to such points only as may serve to illustrate 

 the geology of the district. 



Previously to the commencement of these works, in 1867, the 

 ground intended to be occupied was, for the most part, a vast 

 mud-flat, covered at every tide by the waters of the harbour. The 

 mud, of which I shall have more to say hereafter, was of the soft 

 and sticky character so prevalent in tidal basins, and attained over 

 some parts of the area to the formidable depth of from 35 to 40 feet. 



In 1868 the sea was excluded by means of a dam of sheet-piling ; 

 and the enclosed area has been since reduced, by pumping and deep 

 drainage, to almost perfect dryness to the depth of 40 feet beneath 

 low water. 



Excavations had been already commenced in the higher portion of 

 the ground before the shutting out of the sea- water ; and in 1867 I 

 heard from my brother, Mr. C. H. Meyer, that fossils of the London 

 clay were being met with in abundance. 



In the spring of 1868, when I first visited the works, a fine 

 section nearly 500 feet in length was exposed to a depth of 60 feet» 

 It consisted of : — 



Gravel 10 to 20 feet. 



Stiff clay, withSeptaria 30 to 40 feet. 



A band of rounded black pebbles in clay 8 inches 



Sands and shell -rock 10 feet. 



The fossils of the clay with Septaria were clearly London-clay 

 species. Those of the sands and shell-rock appeared to represent 

 more nearly an equivalent to the Bognor fauna ; but I was puzzled 

 by many of the species, and determined to watch the progress of 

 the excavations. 



New sections have been from time to time exposed since 1868, 

 untn in August of the present year (1870) the excavations had so 

 far progressed as to have opened out clear and nearly continuous, 

 sections of all the strata likely to be seen within the area of the 

 works. 



Description of Strata. 



The strata exposed in 1870, exclusive of alluvial deposits, amounted 

 to a thickness of 97 feet. To this must be added a thickness of 



